The Coronary Artery Surgery Trial is designed to compare medical with surgical therapy in certain well-defined subsets of patients with coronary heart disease by means of randomized studies and to chart the natural history of coronary heart disease in large numbers of patients by means of a patient registry. Eleven clinical sites and a coordinating center having designed a protocol for collaborative studies are now embarking on the patient recruitment phase of this prospective clinical study of coronary heart disease. It consists of two major interlocking aspects, i.e., registry and randomized studies. This contractor is one of five additional clinical sites participating in this effort.